The tape is strong, thin, sticks well to almost any surface, and comes off easily. Each roll has 10 yards of tape so it should last a really long time.
The red line in the center is aligned with the needle of your machine, and the black lines on either side are 1/4″ to each side from the center of the lines, to represent a 1/4″ seam allowance. The black lines won’t replace a piecing foot with a perfect 1/4″, but act as an extra guide.